1. Field of the Invention
The present invention relates to a semiconductor fabrication technology; and, more particularly, to a method for fabricating a Schottky barrier tunnel transistor (SBTT) using a Schottky barrier between a metal and a semiconductor.
2. Description of Related Art
The recent advance of semiconductor fabrication technologies makes it possible to fabricate semiconductor devices having a short channel of 50 nm or less. However, as the size of the devices becomes smaller, new phenomenon occurs which deteriorates operation characteristics of the devices. Specifically, a transistor having a channel length of 100 nm or less must be carefully controlled because a leakage current caused by a short channel effect significantly increases.
To solve this problem, studies have been conducted on SBTT devices in which a source region and a drain region are formed of metal or silicide.
FIG. 1 is a cross-sectional view of a conventional SBTT.
Referring to FIG. 1, the conventional SBTT includes a support substrate 10, a buried oxide layer (BOX) 11 formed on the support substrate 10, a source/drain region 12 formed within a silicon layer on the buried oxide layer 11, a gate insulating layer 13 formed on a channel region 16 of the silicon layer, a gate electrode 14 formed on the gate insulating layer 13, and spacers 15 formed on both sidewalls of the gate electrode 14.
The conventional SBTT has a vertical structure in which the gate insulating layer 13 and the gate electrode 14 are sequentially stacked on the silicon layer. This vertical structure is similar to a typical metal oxide semiconductor field effect transistor (MOSFET) structure. However, unlike the MOSFET, the source/drain region 12 is formed by a sputtering process, not an ion implantation process. More specifically, after a metal layer is deposited by a sputtering process, a thermal treatment is performed to react the metal layer with silicon, thereby forming a metal silicide layer. At this point, a metal silicide layer 17 is also formed on the gate electrode 14.
However, since the gate electrode is first formed and the source/drain region is then formed by the silicide process using a rare earth metal having a very strong reactivity, the spacers on both sidewalls of the gate electrode are damaged during the silicide process. Further, a leakage current may be generated from the damaged region.